Generally, in the production of semiconductor devices, in order to enhance adherability of a resist solution to a wafer, a liquid material for changing a hydrophilic surface to a hydrophobic surface is vaporized by a vaporizer and a surface treatment of the wafer is performed using the vaporized liquid material. As a vaporizer of this type, for example, a vaporizer is used which vaporizes a liquid material by heating the liquid material with a heater.
The liquid material vaporized by the vaporizer is normally supplied by a carrier gas to a wafer housed in a chamber. In this case, a mixture gas of the vaporized liquid material and the carrier gas is supplied to the wafer, and a problem may occur in which, for example, a fluctuation in a concentration of the liquid material in the mixture gas during treatment undermines uniformity of the treatment. Therefore, in order to perform surface treatment in a stable manner, the concentration of the liquid material in the mixture gas must kept constant during treatment.
In order to avoid such a problem, for example, Patent Document 1 discloses a configuration in which the inside of a vaporizer is filled with granules to form a porous body in the vaporizer and in which a heater for heating a liquid material is provided on the outside of the porous body. According to this configuration, the liquid material can be vaporized by introducing the liquid material into gaps in the porous body and heating the liquid material introduced into the gaps by a heater via the porous body. In this case, since a contact area between the porous body and the liquid material can be increased, vaporization of the liquid material can be promoted. As a result, it is expected that the concentration of the liquid material in the mixture gas during treatment can be kept constant.
Patent Document 1: Japanese Patent Application Laid-open No. 2001-295050